1 nanotech project 2008 / phase 2 project: team: accoto celso adham mohamed larrieu jeancharles le...

1ÉC OLE POL Y TEC H NIQ U EFÉ DÉRALE D E LA USANNE

Nanotech Project 2008 / Phase 2Project:Team:

ACCOTO CelsoADHAM Mohamed

LARRIEU JeanCharles

LE GROS ChristopheMAQUEDA LÓPEZ Mariazel OTTONELLO BRIANO Floria

PIZZATO DanielSADRINI Jury

Team Members:

Interferometric Modulator Display

Presentation 4: Anatomy of an iMod



Introduction

Presentation 3:• We are designing a new MEMS based

Display based on a Fabrey Perot Interferometer (iMod)

Previous Problems: - Actuation voltage too high - process: insulating material (PMMA)

would have melted…

Agenda: 1. New Design2. Simulations3. Fabrication



Improving the Design

Last time, we planned to:

• Changed physical design Modify back electrode of device

• Materials More compliant materials

• Thicknesses Thinner back plate (technology issue)

• Lengths Resolution is a constraint

• Boost V Low power constraint



New ANSYS Design

New single IMOD model:two beams support the

reflective plate

Former design



MATBLAB Simulations

Why did we simulate our model on MATLAB?• it’s difficult to set design parameters on ANSYS• to have an idea of the values that we will use on ANSYS for the dynamic simulation

Hypothesis: 1) Static simulation: just a look at the final state of the system

▪ No viscosity forces▪ No switching time analysis

2) Clamped beam modeling of the system3) Everything is made with poly-Silicon



MATBLAB Results

Dimensions:

• 20 μm plate

• Displacement function of the voltage (3 to 6 V)

Vertical position of beam along its length



MATBLAB Results

New Design:

Lenght Voltqge

8 μm 31.1 V

10 μm 22.3 V

12 μm 16.9 V

14 μm 13.4 V

16 μm 11.0 V

18 μm 9.2 V

20 μm 7.8 V



MATBLAB Results: comparison

Results:@ 20 μm: from 30 V to 7.8V

26 % improvement changing the design!



Choice of the design

Adv: residual stress just twist the structure.

Dis: difficult to design.Adv: beams instead of plate



ANSYS Design

New design:

• From plate to beam• Less stiff system• Plate parallel to

substrate



ANSYS Simulation Difficulties…

• 400 lines code• 34 3-D points (102

positions)

• Problems in the meshing• Problems assembling the

system



Process Flow & Mask Design

New process flow:

- Previous mistakes- New design

Mask modeling:

- AutoCAD

Eg. of mask

... Still preliminary



Process Flow

Glass substrate

Silver deposition: sputtering



Silver deposition:sputtering

Process Flow



Resist deposition

Process Flow



Mask 1

Process Flow



Etching

Process Flow



Dielectric layer

Process Flow



Mask 1

Resist+etch+resist removal

Process Flow



SiO2 layer: PECVD

Process Flow



Mask 2

Resist: DQN

Process Flow



SiO2 etch 80 nmexactly

Process Flow



Mask 3

Resist: DQN

Process Flow



SiO2 etch 50 nmexactly

Process Flow



Remove DQN

Process Flow



Deposition of Al:Reflective layer

Process Flow



Mask 4

Deposition of protective squares

Process Flow



Etch of Al +Removal of protective

squares

Process Flow



SiO2 deposition

Process Flow



Mask 5

Etching of SiO2

Process Flow



Mask 6

Etching of SiO2

Process Flow



SiN deposition

Process Flow



Mask 7

Etching of SiO2

Process Flow



V+

Concept of the system

Column selection

Row selection

ProcessorTSP 65131

Vhold

V+ V-

Battery

“Operating Principles of Mirasol Displays: Interferometric Modulation (IMOD) Drive”, QUALCOMM December 2007

Vhold

V-



“Operating Principles of Mirasol Displays: Interferometric Modulation (IMOD) Drive”, QUALCOMM December 2007

PSPICE Design



• Mask is the 1st approximation of the fabrication process

• Final masks for the process are under review

• Ansys/Matlab:

• Less stiff beams → lower activation voltage: 8V

• Vibration analysis and switching time to be checked

• PSPICE

• Addressing circuit has been defined

• Power consumption has been evaluated

Conclusions



Thank you for your attention!

1 nanotech project 2008 / phase 2 project: team: accoto celso adham mohamed larrieu jeancharles le...

Documents

nanotech project

ansys design new design

design adv

design parameters

etching process flow

matblab resultsnew design

sputteringprocess flow

dielectric layer process